use of Functions to write python program.pptx

Functions in
PYTHON
Rahul Singh Sikarwar

Functions
• A function is a device that groups a set of statements so they
can be run more than once in a program—a packaged
procedure invoked by name
• Functions also can compute a result value and let us specify
parameters that serve as function inputs and may differ each
time the code is run.
• More fundamentally, functions are the alternative to
programming by cutting and pasting—rather than having
multiple redundant copies of an operation’s code, we can
factor it into a single function.

Function-related statements and
expressions

Introduction
• Functions are a nearly universal program-structuring device.
You may have come across them before in other languages,
where they may have been called subroutines or procedures.
• As a brief introduction, functions serve two primary
development roles:
1. Maximizing code reuse and minimizing redundancy
2. Procedural decomposition

• def is executable code. Python functions are written with a new
statement, the def.
 def is an executable statement—your function does not exist until
Python reaches and runs the def. In fact, it’s legal (and even
occasionally useful) to nest def statements inside if statements,
while loops, and even other defs.
• def creates an object and assigns it to a name.: When Python
reaches and runs a def statement, it generates a new function
object and assigns it to the function’s name. As with all
assignments, the function name becomes a reference to the
function object
• lambda creates an object but returns it as a result: Functions
may also be created with the lambda expression, a feature that
allows us to in-line function definitions in places where a def
statement won’t work syntactically.

• return sends a result object back to the caller: When a
function is called, the caller stops until the function finishes its
work and returns control to the caller. Functions that compute
a value send it back to the caller with a return statement; the
returned value becomes the result of the function call. A return
without a value simply returns to the caller
• yield sends a result object back to the caller, but
remembers where it left off. Functions known as generators
may also use the yield statement to send back a value and
suspend their state such that they may be resumed later, to
produce a series of results over time

def Statements
• The def statement creates a function object and assigns it to a name. Its general format is as follows:
def name(arg1, arg2,... argN):
Statements
Function bodies often contain a return statement:
def name(arg1, arg2,... argN):
...
return value
The Python return statement can show up anywhere in a function body; when reached, it ends the
function call and sends a result back to the caller. The return statement consists of an optional object
value expression that gives the function’s result. If the value is omitted, return sends back a None.

nest a function def inside an if statement to
select between alternative definitions:
if test:
def func(): # Define func this way
...
else:
def func(): # Or else this way
...
...
func() # Call the version selected and built

A First Example: Definitions and Calls
Definition:
Here’s a definition typed interactively that defines a function called
times, which returns the product of its two arguments:
>>> def times(x, y): # Create and assign function
... return x * y # Body executed when called
...
>>> times(2, 4) # Arguments in parentheses
8

Python program for solving a quadratic equation of the form ax
2
+bx+c=0
1. Use function def() to find the solution
2. a ,b and c is user input.
Input 1: a= 1, b=-3, c=2
Input 2: a= 1, b=-8, c=5
Input 3: a=5, b= 20, c= 32

use of Functions to write python program.pptx

use of Functions to write python program.pptx

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